This invention relates to fluid jet cutting systems, and more specifically, the energy-dissipating receptacle associated with such systems.
Cutting by means of a high-velocity fluid jet is well known in the art. Typically, a fluid such as water, at a pressure of 55,000 pounds per square inch, is forced through a jewel nozzle having a diameter of 0.003 to 0.030 inches to generate a jet having a velocity of up to three times the speed of sound. The jet thus produced can be used to cut through a variety of metallic and non-metallic materials such as steel, aluminum, paper, rubber, plastics, Kevlar, gravite and food products.
To enhance the cutting power of the fluid jet, abrasive materials have been added to the jet stream to produce a so-called "abrasive-jet". The abrasive-jet is used to precisely and accurately cut a wide variety of exceptionally hard materials such as tool steel, armor plate, certain ceramics and bullet proof glass, as well as certain soft materials such as lead. Typical abrasive materials include garnet, silica and aluminum oxide having grit sizes of #36 through #120. As used herein, the term "fluid jet" is used generically to means fluid jets and abrasive jets.
Typically, a fluid jet cutting system includes a nozzle for producing an axially directed high velocity cutting jet formed from a liquid; and means for positioning a workpiece axially downstream from the nozzle to be cut by said jet.
The high energy of the fluid jet must some how be absorbed once it has passed through the workpiece. Not only is the jet a danger to persons or equipment which might accidentally be impinged, but the fluid forming the jet must also be collected for proper disposal. Fluid-jet cutting systems have accordingly included an energy-dissipating receptacle for receiving the high-velocity jet of fluid after it emerges from the workpiece. For example, U.S Pat. Nos. 2,985,050 and 3,212,378 disclose a catch tank containing water or other fluid above a resilient pad of rubber or neoprene or other elastomeric material. Spray rails are provided on each side of the tank with a water spray being directed downwardly over the liquid surface to blanket the vapors of the cutting fluid and prevent their disbursal in the area of the cutting machine.
U.S. Pat. No. 3,730,040 discloses an energy-absorbing receptacle containing a hardened steel impact block at the bottom of the receptacle, and a frusto-conical baffle arrangement immediately adjacent the workpiece at the top of the receptacle. The jet passes into the receptacle, and through a liquid in the receptacle which absorbs a portion of the jet's energy. The jet thereafter impacts the steel block at the bottom of the receptacle. The orientation of the baffle plates are described as preventing sound, spray and vapor from passing back out of the entrance.
U.S. Pat. No. 4,669,229 discloses an energy-dissipating receptacle, whose interior cavity has side-walls which generally converge in the direction of jet flow. A plurality of circulating suspensoids within the cavity are impinged upon by the jet to dissipate the jet's kinetic energy. U.S. Pat. No. 4,669,229 is assigned to the assignee of this invention, and its contents are hereby incorporated by reference.
All of the foregoing receptacles have certain design criteria in common. First, means must be provided for the evacuation of spent fluid, kerf material and abrasive (in the case of abrasive jet cutting systems) from the receptical. Secondly, it has been found that the entrance of the receptacle preferably includes a wear-resistant lining, despite the considerable added cost. Third, the substantial noise generated by the fluid jet entering into air after cutting the workpiece, must be minimized by minimizing the open space between the cut material and the energy-dissipating interior of the receptacle. As those skilled in the art appreciate, noise is reduced to a minimum when there is direct contact between the energy-dissipating interior and the workpiece.